PROJECTSUMMARY A major goal of mosquito research is improved methodologies for control of the diseases transmitted by these insects. The mosquito?s sensory systems provide all the information for identifyinghumanhosts,choosingsitesforegglaying,andalltheotherbehaviorsusedbythis organism. This project focuses on the mosquito?s visual capabilities. The R1-6 cells are the majorclassofphotoreceptorsoftheadultmosquito.Thesecellsprovidethesensorycapability needed for the formation of visual images required for navigation and object recognition. The R1-6 photoreceptors of Aedes mosquitoes also possess a specialized feature in which the light sensor of these cells, the Aaop1 rhodopsin, is actively removed from the photoreceptive membranesindaylightandreturnedtothesemembranesatnight. We seek to understand the role of the R1-6 photoreceptors and the specialized rhodopsin trafficking capability of these cells. Innovative gene-editing capabilities provided by site-specific CRISPR endonucleases will facilitate the creation of an Aedes Aaop1 mutant. The R1-6 photoreceptors will not be capable of light detection in this Aaop1 mutant. Histological analysis will document the importance of Aaop1 in triggering the day-night cycles of remodeling. We will also evaluate the importance of these R1-6 cells in mosquito vision by characterizing the optomotor response of the Aaop1 mutant. The optomotor response is indicative of the mosquito?s capability to respond to information existing within a visual field. Both light intensity and physical characteristics of objects in the visual field will be varied to generate a detailed understanding of the Aaop1 mutant?s visual deficits. Results in the Drosophila system show that arrestins are adapter proteins that bind to light-activated rhodopsin to build the protein complex responsible for light-triggered rhodopsin movement. There are two arrestin genes expressed in Aedes photoreceptors. We will use gene editing to create mutations in both of these genes. Characterization of these two arrestin mutants will determine their specialized roles in Aedes photoreceptors. The effort will test the hypothesis that inability to remove rhodopsin from the photosensitive membranes during the daylight hoursresultsinretinaldegeneration.Wewillusevisualresponsebehaviorstodeterminehow quickly the arrestin mutants and associated retinal degenerative processes compromise the mosquito?svisualcapabilities. Insummary,thisprojectisaninnovativeapproachtocharacterizemosquitovisionand the importance of specialized features of mosquito photoreceptors. Our work will create the first vision-defective mosquito mutants. These mutants provide a unique resource to evaluate theroleofvisioninhostrecognitionandothercomplexmosquitobehaviors.